As magnetic storage technology is pushed to increase the capacity of magnetic media, such as hard disk drives (HDDs), the spacing of the data tracks is becoming less and less. This puts a constraint on the component technology used to both write the data (writer element) and read the data back (sensor element). In the case of writing the data, this constraint has led to shingled magnetic recording (SMR) where writing is performed in a path wider than the actual data track, an offset of the writer is introduced by one track position, and writing is performed again.
SMR is a recording system that offers higher areal density than other conventional designs. In conventional SMR systems, a main pole of a magnetic head is used to write tracks in a shingled arrangement, progressively overlaying a portion of a previously recorded track when a new track is recorded, hence the descriptive name, such that recording is performed with overlapping tracks. Consequently, the actual tracks are recorded using track edge portions of the main pole, so the recording characteristics of the main pole track edge are somewhat determinative of overall system performance. That is to say, it is of great utility to improve the field gradient in the cross-track direction and furthermore to improve the field gradient in the down-track direction, particularly at a position of the magnetic head corresponding to the track edge.
Bit patterned recording (BPR) technology is intrinsically a low bit aspect ratio (BAR) technology that uses high data track per inch (TPI) configurations. Reductions in servo track mis-registration, write head track width dimensions and read head track width dimensions are used to support BPR media and its higher TPI configurations. There are technology options available to improve servo track mis-registration, such as micro-actuators and sealed drives. Similarly, write head track width dimensional reduction may be alleviated by the introduction of shingled recording in which the write track width is larger than the final recorded data track width. However, there is currently no similar solution to alleviate the read track width reduction requirement.